Should I wait until I get tenure to have a baby? That is the question I was most frequently asked by female graduate students when I was dean of graduate studies at U.C. Berkeley. These women, who comprised at least 50 percent of the division, knew about the research I was doing with Nicholas Wolfinger and Marc Goulden on the effect of children on academic careers.

My answer: Family formation negatively affects women’s, but not men’s, academic careers. For men having children is a career advantage, and for women it is a career killer. And women who do advance through the faculty ranks do so at a high price. They are far less likely to be married with children. Among tenured faculty 70 percent of men are married with children compared with 44 percent of the women.

Academia is difficult for mothers because of the rigid lockstep career track that puts the greatest pressure on aspirants in their 30s and 40s.

What makes academia so difficult for mothers? In large part it's because academia is a rigid lockstep career track that does not allow for time out and puts the greatest pressure on its aspirants in the critical early years. Most Ph.D.'s are achieved, postdoctoral fellowships completed and tenure granted between the ages 30 and 40; the "make or break decade" as I call it. It is also the decade in which women have children, if they have them at all. Low fertility is not a coincidence among tenured women, who believe they must have tenure (usually around 40) before beginning a family. Achieving tenure used to be several years earlier. But most universities still do little to provide a more flexible career path or to put in place family responsive programs that would make it possible to balance work, particularly for graduate students and postdoctoral candidates.

Is academia more punishing for mothers than other professions? Well, yes. According to census data, among the professions charted — faculty members, physicians, lawyers and chief executives, between the ages of 35 and 50 — women in academia, no matter how many hours they worked, reported fewer children than women in all other professional fields. Among female faculty members who worked between 50 and 59 hours a week, 41 percent reported children in the household, compared with a robust 67 percent for female doctors.

We all know what structural changes -- like paid family leave for both mothers and fathers, a flexible workplace, a re-entry policy, pay equity reviews, childcare and dual-career assistance -- would help to level the playing field. Those universities who have these policies and have enforced them have found an advantage in recruitment and retention. After new family policies were put in place at Berkeley, we experienced a baby boom: twice as many babies were born to female assistant professors.

So, beware, if having children is important to you, investigate the family friendly policies of the universities you are considering for graduate school or faculty positions.

Correction: A previous version of this post misspelled the name of a co-researcher on a study of the effect of children on academic careers. It is Nicholas Wolfinger, not Nicholas Wolginger.